If he retires in 2022, 2022 becomes his first RMD year and any distribution made during that year, including those made before retirement, is RMD until the RMD for the year is satisfied, ineligible for rollover. If the entire 401(k) is rolled over in 2022 and he then retires later in 2022, the distribution that was rolled over reverts to having been partially RMD and an RMD that was impermissibly rolled over to the IRA. The part that was impermissibly rolled must be treated as a regular contribution to the IRA and an excess contribution to the extent that it exceeds the amount that he is eligible to contribute as a new contribution for 2022. The relative dates of the distribution and retirement are immaterial. It doesn't matter in which order they occur within the same calendar year, the consequences are the same.
